The invention disclosed herein relates to machines for applying closures to containers such as bottles and, particularly, to a device for filling the necks of the bottles with inert gas in the free space above the liquid level before the closure is applied.
In machines for filling and applying closures to bottles containing a liquid, such as beer, which is sensitive to oxygen, it is necessary to purge the air from the necks of the bottle and replace the air with a non-oxidizing gas such as carbon dioxide. A variety of devices for supplanting the air above the liquid level in a container with inert gas are known. Most of the devices use nozzles that project carbon dioxide into the bottle through its mouth and into the space above the neck of the bottle and the descending enclosure applying ram.
German Patent No. DE32 26 172 discloses a procedure for replacing the air in the neck of nearly filled bottles with inert gas. In the patented machine, warm inert gas is first introduced into the bottle neck to dissolve or suppress bubbles which may have remained inside at the top of the liquid. Subsequently, inert gas is injected directly toward the mouth of the bottle by means of nozzles in order to eliminate the air contained in the neck and to substitute the inert gas. After the inert gas is injected, crown caps are advanced on a magnetic holder and pressed onto the bottle mouth with a cylindrical head that has a tapered or bell-shaped hole that crimps the caps. The nozzles are attached to the vertically reciprocating head that presses the cap onto the bottle.
With the known device, the bell-shaped opening on the capping head must encompass the bottle mouth before creating an inert gas ambient for exclusion of air can be assured. Thus, only a short time is allowed for the nozzle to expel the air from the empty space in the bottle neck, from the hollow space in the sealing cap and from the space between the bottle opening and sealing cap. The time between entry of the bottle in the bell-shaped capping head and application of the closure cap is so short that purging of air in the spaces mentioned is incomplete by this method. Furthermore, introduction of the sealing caps under the sealing cone is difficult since this must be done through a lateral opening in the bell-shaped head.
In German Patent No. DE-AS 19 10 548, bottles filled with liquid that degrades by exposure to oxygen are first completely filled in a carbon dioxide atmosphere and, before applying the caps, liquid is displaced from the bottle by carbon dioxide. In this patent, the bottles are filled to the rim with liquid and are moved under the sealing device. During lowering of the sealing head, high pressure carbon dioxide is blown from below and lateral to the bottle opening, against the sealing cap and the bottle is sealed during continuous injection of carbon dioxide. In this arrangement, immediately before sealing, carbon dioxide is blown under high pressure by means of nozzles, which are arranged below a bottle centering bell, and against the bottom side of the crown cap so that the gas deflects off the cap and against the liquid surface in the bottle. As a result of the carbon dioxide being blown in, part of the liquid is displaced from the bottle opening so that an empty space is created which is supposedly filled with pure carbon dioxide.
One disadvantage of the known procedure just described is that, due to the impact of carbon dioxide deflected off of the inner side or bottom side of the crown cap, the displacement or overflow of an unpredictable amount of contents of the bottle must be tolerated. Besides, in the bottle neck a complete displacement of air by carbon dioxide cannot be assured. Using the bottom side of a crown cap as a gas stream deflecting surface does not result in the desired efficiency of air displacement by carbon dioxide emitted from nozzles which must be arranged relatively far below the bottle mouth or opening.